1. Field of the Invention
The present invention relates to an image processing apparatus, an imaging apparatus, an image processing method, and a computer program product, and, more particularly to removal of noise.
2. Description of the Related Art
In recent years, in a digital still camera (hereinafter, “digital camera”), an increase in the number of pixels of a charge coupled device (CCD) has occurred. On the other hand, according to the increase in the number of pixels of the CCD, sensitivity of the CCD has deteriorated.
As a solution for such a problem, an imaging apparatus that adds up pixels of a plurality of images is disclosed in Japanese Patent Application Laid-Open No. 2005-44915. In such an imaging apparatus, it is possible to improve sensitivity by adding up the pixels of the images.
When images are picked up with improved sensitivity, noise is emphasized. A technique for removing noise by setting a cutoff frequency of a low-pass filter according to imaging sensitivity is disclosed in Japanese Patent Application Laid-Open No. 2004-297731.
However, as disclosed in Japanese Patent Application Laid-Open No. 2005-44915, explosure time is long because the pixels of the images are added up. Although the long exposure time causes no problem when a camera is fixed and a subject does not move, positional deviation occurs when the camera or the subject moves.
In the technology described in Japanese Patent Application Laid-Open No. 2004-297731, although it is possible to remove noise according to the imaging sensitivity, edges of the image blur. For example, if sensitivity is set high when an image is taken in a bright place, strong blur processing is applied to the image with less noise to blur in the image more than necessary.